Interactive Volume Visualization of General Polyhedral Grids Philipp Muigg 1,3 , Markus Hadwiger 2 , Helmut Doleisch 3 , M. Eduard Gröller 1 1, Vienna University of Technology, Austria 2, King Abdullah University of Science and Technology, Saudi Arabia 3, SimVis GmbH, Vienna, Austria
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Interactive Volume Visualization of General Polyhedral Grids
Interactive Volume Visualization of General Polyhedral Grids. Philipp Muigg 1,3 , Markus Hadwiger 2 , Helmut Doleisch 3 , M. Eduard Gröller 1 1, Vienna University of Technology, Austria 2, King Abdullah University of Science and Technology, Saudi Arabia 3, SimVis GmbH, Vienna, Austria. - PowerPoint PPT Presentation
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Interactive Volume Visualization of General Polyhedral Grids
Philipp Muigg1,3, Markus Hadwiger2, Helmut Doleisch3, M. Eduard Gröller1
1, Vienna University of Technology, Austria
2, King Abdullah University of Science and Technology, Saudi Arabia
3, SimVis GmbH, Vienna, Austria
Motivation
• Computational Fluid Dynamics (CFD) simulations• Increase in size• Meshes become more complex
Motivation
• Many unstructured grid volume visualization techniques limited to tetrahedral grids
• Direct volume rendering for grids composed of general polyhedral cells
• Data structure to represent polyhedral grids• Low memory footprint• Support traversal operations required by ray casting
Data Structure
• Requirements for ray casting• Query all faces of a cell• Query neighouring cell across a face• Query vertices of a face
Data Structure
• 2D illustration• 3D Faces 2D Edges• 3D Cells 2D Faces
• Example contains• 6 „faces“• 3 „cells“
• Common grid representations cell centered
Data Structure
6 links
Data Structure
• Common grid representations cell centered• Cell to cell traversal for ray casting requires
(redundant) face connectivity
Data Structure
• Redundancy• Cell to face data derivable from face to cell data• Face to cell data derivable from cell to face data
21 links
Data Structure: TSFL
• Two sided face lists (TSFL)• Face based
(comparable to winged/half edge)• Cells represented via linked lists• Two links per face
(front and back link)
Data Structure: TSFL
• Additional bit flag per link (front and back flag)• Blue facing towards cell• Green facing away from cell
Data Structure: TSFL
• Visit all faces of a cell via links• Select link at face based on previous flag• Step from one cell to neighbour
by selecting other link
12 links
Data Structure: TSFSL
• Two sided face sequence lists (TSFSL)• Group faces facing towards same cell• Discard front links
(retain last in sequence)
Data Structure: TSFSL
• Two sided face sequence lists (TSFSL)• Group faces facing towards same cell• Discard front links
(retain last in sequence)
9 links
Data Structure: TSFSL
• Requirements for ray casting
Query all faces of a cell
Query neighouring cell across a face• Query vertices of a face
Data Structure: TSFSL
• TSFSL storage• Interleave mesh connectivity and face geometry• Back links stored in front of face geometry• Terminating front link stored at end of sequence (sequence
terminator)• Entire mesh stored in single 1D array
HAVS [Callahan 2005]: ~7-9 byte/tet GPU and 118-149 byte/tet CPU
Tet Strips [Weiler 2004]: ~15 byte/tet
Cells/Faces 1.5M/4.7M 1.3M/8.9M
Tetrahedra 17M 89M
Byte/Tetrahedra 8.5 byte/tet 7.5 byte/tet
Bricks/Overhead 4/1.7% 10/8.6%
Render Time (preview) 222ms (81ms) 2.9s (742ms)
Summary/Future Work
• TSFSL data structure• Face based• Low memory footprint
• GPU-based ray-casting on polyhedral meshes• Works directly on TSFSL• Domain decomposition for culling/depth peeling
• Future Work• Utilize CUDA/OpenCL shared memory during ray-casting• Parallelize across multiple GPUs
Questions?
Thank you for your attention!
Acknowledgements:Polyhedral datasets courtesy of CD-Adapco
Cooling jacket and Diesel Particulate Filter datasets courtesy of AVL List GmbH, Graz, Austria
Parts of this project have been funded by the Austrian Research Funding Agency (FFG) in the scope of the project AutARG (No. 819352) and the ScaleVS (WWTF) project